When a three-dimensional image is produced, two video signals corresponding to left and right fields of a view of a human being are needed.
In order to reproduce a three-dimensional image, a synchronized recording and reproducing system capable in which two video signals are transmitted simultaneously and two video tape recorders (VTRs) are used has been so far used. According to this system, there arise various disadvantages. A first disadvantage is that a television signal transmission capacity must be doubled in comparison to a single transmission system. A second disadvantage is the increase in cost because two VTRs must be used. A third disadvantage is that precision circuits for correctly synchronizing two video signals and new transmission systems are required so that a delicate parallax is expressed.
In view of the above, there has been proposed a system in which information to be transmitted is suitably compressed by utilizing characteristics of a stereoscopic image.
For instance, Japanese Laid-open Patent Application No. 54-111371 filed by the same applicant discloses in a specification of "a distance measurement system" in which a suitable number of sampling points are selected on each line and it is assumed that a right picture is defined by a shift of a left picture so that an amount of the shift between the left and right pictures and the left picture are transmitted.
According to this system, the shift information must be transmitted for each line, so that the number of the shift information is increased as much as MN, where M is the number of sampling points on each line and N is the number of lines.
Furthermore, when a hexahedral object as shown in FIG. 1A is picked up by left and right television cameras, it is assumed that there exists a stereoscopic image having the left picture including the faces A, B and C and the right picture including the faces A, B and D are obtained. The face D is picked up by the right television camera so that it is contained in the right picture, but the left picture does not contain any information about the face D which is behind the scene in the left picture. As a result, even when the left image data (represented by dots) along the horizontal scanning line extended across the left picture as show in FIG. 1B is shifted rightward, it is impossible to obtain data corresponding to the face D in the right picture data. As a result, the reproduction of the right picture is not sufficient, so that unnatural pictures perceived by left and right eyes cause fatigue in the case of a long program.
In addition, according to this system, the left picture is shifted rightward to define the right picture from the left picture and thus in the case of a stereoscopic television system as shown in FIG. 2, of the left picture LCI picked up by a left camera LC and the right picture RCI picked up by a right camera RC, the left picture LCI is shifted rightward. In this case, it is possible to reproduce a right picture from the left picture picked up by the left camera LC for a rear object RO marked x at a longer distance from the left and right cameras LC and RC, but an object FO marked at a shorter distance from the left and right cameras LC and RC cannot be reproduced in the right picture from the left picture. As a result, it has been impossible to reproduce a three-dimensional image of an object moving forward or toward the left and right cameras LC and RC. Furthermore, according to this system, the right picture is reproduced by merely shifting the positions of the picture data on the horizontal lines in the left picture, so that a fine image is defined by a zig-zag line.
As described above, the prior art stereoscopic television picture transmission system has defects that its transmission band is unnecessarily broad because redundant information is transmitted and that required information is dropped because of unsatisfactory compression of information.